FS#1692 - Issue with Layouts. "Viewport" enteties are not highlighted in "Black/White Mode"

QCad 3.19.2 Professional, 64bit, Linux Mint

Case:1. Open some drawing with viewport entities on layout block (paper scace). Print Preview mode is “On” automatically.2. Switch to “Black/White Mode” from toolbar and move cursor on “Viewport” enteties. This entitie is not highlighted. With other enteties all works as expected.In “Full Color Mode” and “Grayscale Mode” no problems.